Certified Landscape Irrigation Auditors use a complicated mathematical formula to determine the “Distribution Uniformity Lowest Quarter”.

Copy and paste DUlq into Google and a more detailed explanation can be had.

In essence, the amount of water necessary to supply the driest is 25% of the yard needs to be factored in. 100% distribution uniformity is impossible.

This is why proper irrigation design is so important.

If a system is only 45% efficient (very common) 55% of the water will be wasted trying to supply enough water to the “lowest quarter.”

The “throw water in the air” sprinkler system design approach favored by uneducated “irrigation designers” will soon come to an end.

Thank goodness. None us us can afford those guys anymore.